Flexible sprocket hub



Dec. 23, 1952 E. 1 MCINTYRE ELEXIBLE sPRocKET HUB Filed May 21, 1949 www Patented Dec. 23, 1952 FLEXIBLE SPR-OCKET HUB Elmer L. McIntyre, Detroit, Mich., assigner to Morse Chain Company, Ithaca, N. Y., a corporation of New York Application May 21, 1949, Serial No. 94,680

( ci. (s4-27) 1 cnam. 1

This invention relates in general to sprockets for power transmission means and is particularly concerned with a flexible sprocket hub construction providing a means of connecting the sprocket to a shaft through a flexible medium particularly characterized as being of the series spring type.

A flexible sprocket hub construction incorporating a flexible medium as contemplated by this invention is particularly advantageous because it reduces the magnitude of shock load transmitted from the driving member to the driven member. In accordance with the construction of the present invention the drive is so constructed that the flexibility of the connecting flexible medium can be controlled by the respective arrangement and the number of flexible trunnion blocks incorporated in the device so as to tune the natural frequency of the system out of the range of the frequency of exciting torque.

It is recognized that in the prior art numerous attempts have been made to provide a flexible sprocket hub of this general class and efforts have been made to overcome the various deciencies found in such prior art structures, but to the best of the applicants knowledge the prior art structures have had only limited success, and have been accorded only limited commercial recognition. It is believed that this fact results from apparent deciencies of the prior art structures, their nonadaptability for universal application and their expensive construction which so greatly'increased the cost as to seriously handicap sales acceptance.

The present improvement in flexible sprocket hubs is directed to simplify their construction and their mode of operation and also to provide a flexible sprocket hub which may readily and conveniently be employed universally to various types of sprocket assemblies presently being commercially exploited. Moreover, the present device seeks to employ conventional parts wherever necessary and expedient, thereby to effect a substantial reduction in cost over prevailing types of flexible sprocket hub assemblies presently being employed.

Accordingly, an object and accomplishment of the invention is to provide a flexible sprocket hub assembly comprising a sprocket and flanged hub, the sprocket being arranged for a free llt on the flange hub and being maintained end- Wise by suitable means such as, for example, a

.snap ring. Operatively disposed between the sprocket and the flanged hub, in a series spring relationship, there' is disposed a number of trunnion blocks having a like number of driving pins alternatively arranged so that one pin is associated with the sprocket while the next pin would be associated with the flanged hub. The load on the sprocket being through the pin by the trunnion block and thereafter to the driven shaft via the hub. An increase in absorption of the shock load by the trunnion blocks is accomplished by having a greater portion of at least one side in spaced relation to the sprocket or the hub to allow for volumetric expansion of said block.

A further object and accomplishment of the invention is to provide a flexible'sprocket hub assembly designed for advantageous employment in power transmission equipment and which shall have a novel and compact arrangement of parts wherein said parts can be readily assembled and serviced.

The invention seeks, as a further object and accomplishment, to provide a flexible sprocket hub as contemplated herein and characterized by an arrangement of parts to more'advantageously and satisfactorily perform the function required of it and adapted to provide a compact unit which will successfully combine the factors of structural simplicity and durability, and yet be economical to manufacture.

An important object and accomplishment of the invention is to provide a flexible sprocket hub incorporating a ilexible medium, said flexible sprocket hub being particularly and advantageously applicable for employment in power transmission equipment where freedom from vibration and shock is desired, said flexible sprocket hub being particularly characterized in its simple but sturdy construction and in its convenient, fool-proof and safe operation.

A more detailed object and accomplishment of the invention is to provide a flexible sprocket hub assembly incorporating a flexible medium employing principles of construction and operation whereby the flexible medium imparts a series spring system as distinguished from a parallel spring system. It is notable that in series spring systems of the type as contemplated herein the deflection of the trunnion members are additive. This type of system gives less load carrying capacity than the parallel type system but provides more flexibility which may be highly desirable in many applications. k

Another particular object and accomplishment of the invention is to provide a flexible sprocket hub incorporating a, flexible medium by co-relating and especially designing the various elements of such sprocket hub assembly whereby there shall be cooperation between said improved elements as will best serve the purpose of providing an eiicient flexible sprocket hub assembly capable of being manufactured at low cost and yet giving the maximum of service in use.

Additional f objects, features and advantages of the inventiondisclosed herein will be .apparent to persons skilled in the art after the construction and operation are understood from the within description.

It is preferred to accomplish the various objects of the invention and to practice the "same-in substantially the manner asV hereinafter more fully described, and, as more particularly pointed out in the appended claim.

With the above and otherncidental 'objects in view, the invention has other marked-improvements and superiorities which radically distin- K ,.guishesit `from presentlyknown. structures, ,these .improvements.. in .the invention residing, in v.the

novels construction-rand cooperative; function .of thepartsg thereof fthecombination of .parts and .the arrangement thereof. as, 'illustrated in .the fdrawing-.andwhich willbe moreQfully described hereinafter and particularlyipointed out in the substantially on lthe; .plane` -on the .line 2-f2 in Fig. A 1;

...Fig.. .3v .is .a side elevational. view of.. a. modi-fied flexible sprocket hub assembly contemplated herein; fand :.Fig-Ais. asectiona-l 'viewv ofthe .nexiblesprocket ...assemblydepictedinFig. 3. and ,being taken subl stantially on ,theplane -of theslineAwA in. Fig. 3.

fflhefdrawing. is..to vbe Yunderstood as beingv more' or less of .a schematic character. for the. purpose ...ofillustratingand disclosing .typical or. preferred .'.forms ofthe-improvements.contemplated. herein and in the drawing `.like reference.l characters identifythe same parts in. the several. views.

Inthe., exemplary. embodiment oftheiinvention .depicted in` Figs.. 1 -and 2, .the-flexiblesprocket .hub V.with which.the,.present, invention .is par- ...ticularly ,concernedis ,.designatedin its. entirety bythe numeral 2li` andy comprises, in general, a sprocketI element.. 2 "inthis instance constituting -thedriving Vmemberga angedhub'v 22v carried by a shaft. 23 in -this instance constituting-'thedriven member, said sprocket element .being Yarranged for. a Afree iit,on1..the flangedihubhtopermit re- ,stricted relativerotation therebetween and .being maintainedend-wise.byY suitable means such as,

for. example,. a,snap ring 275, said sprocket elev *ment 2| and .said hanged. hub 22 having operaitively disposed .therebetween a flexible medium l `designated in'itsentirety by the numeral and comprising a plurality of trunnion blocks as at V3| .operatively disposed within a retainer ring.32

. carried for a free 'tlby portions. of the hub. 22

.and being .maintainedc endg-wise by, portions of .the .sprocket element" 2 each of .said trunnion blocks 3| being respectively operatively associated with abushing as at.33 .arranged ina series spring .relatonshimand aplurality of stud blclts Sseach .respectively arranged toV be received'intcr portions of a bushing and so that one stud bolt would be associated with the sprocket while the next stud bolt would be associated with the flanged hub.

The foregoing arrangement is particularly characterized in its mode of operation in that the flexibility of the flexible medium can be controlled by the arrangement and number of the trunnion blocksvas at 3| soas to tune the natural requencywof the system ,out/.offtherange of the frequencies of the exciting torque.

It is notable that the path of the load on the sprocket is arranged so that it is taken through thestud lbolt 34 by the trunnion block 3| and thereafter is.- transmitted to the driven shaft 23 .viaztherhub ange122. This arrangement provides ftorsienal'deflection or wrap-up of the sprocket 2| in relation to the shaft 23. The desired results can -be'also regulated by altering the num .ber and size of trunnion blocks or the radius on which they are mounted.

.In accordance with therconstruction ci.. the

l V present invention the flexible .mediurn t vimparts a series 'spring Y.system asA distinguished from a parallel spring system.

In "this j connection, in series spring systems 'ofthel type' as contemplated Nherein, .the "'deections Aof`A the` trunnion" members "This type of system gives. lessload carrying capacity nbut 'provides more flexibility.; V.thanV jtheparallel `type "systemwwhichrmay' v'be highlyA .desirable in many-applications --Having thus described in generaln the major component Yparts "of Ythe Vflexible sprocket ihub contemplated herein; the IVspecific construction -andncocperative association Vand-.function of the 'parts vof isaidV flexible sprocket hub 'Will-now be describedl indetail.

Although; the description Yhasfgthus4-- far stated that thegsprocket element 2 constitutesA the driving element while theshaft-l23-constitutes the driven elementf-it is obvious that the function of these elements maybe reversed in some-instances soI that the 4sha-ft- 23- maybe'v -the'fdriving `@element while sprocket/element 2 will` vthen be -come the driving member. Y 1

An important feature '-roflfthis invention fis the Iprovision of the Ilflexiblemediumllas vbeing mechanicallyoperatively disposed Y between the sprocket element 2 and the'flangedf'hub-EZj-in a ser-ies relationship to provide a resilientconnectionbetween these elements. The'flexible medi- -um is comprised ofpr-elo'adedV trunnion-blocks as at 3| which-may beformed of a suitable-rubber andwhose' live rnusclej-likel flexibilityv takesV up the'wrap-up of-ftorsional loads; thereby to-protect machine installation towhichthe present flexible sprocket hubV assembly-'maybe adjunctivelyemployed fromv shock;vibrations-and uneven impulses. l\/.[oreover,-v the employment of'flexible trunnion blocks as contemplatedhereinadvantageously limitsy metal-to-metal contact between the driving and driven members-and requires no lubricationfis impervious to Adirt,^dust and Weathl Themuscle-like trunnion blocksv asfat 3 Itare designed for uniform stressand lineandeection,

lall relative movement being accommoda-tedby --the retainer ring 32. Each of the bushings 33 Vare arranged respectively to receive a stud bolt as at 34, said stud bolts having threaded end portions 38 adapted to be received into threaded apertures 3Q in a series spring relationship, that is to say, one stud bolt Would be associated with vthe sprocket while the next stud bolt would be associated with the flanged hub, this arrangement being illustrated in Fig. 2; therefore, when flexible medium 30 is in its assembled relationship as `illustrated in Fig. 2, the trunnion blocks 3| are lpermits them to allow considerable deection even with a light load. Another important feature is that the trunnion blocks 3| are disposed so that a greater portion of both sides thereof are in spaced relation with respect to the sprocket and hub thus increasing the absorption power of the blocks by -allowing volumetric expansion thereof when subjected to shock loads.

Moreover, the design and ,preloading vof the trunnion blocks provide advantageous operation in displacement resulting from thrust loads and accommodates annular deflection and torsional vibration, torsional deflection being overcome by the fact that imposition of a torque load increases pressure in the direction of the load and reduces pressure in the opposite direction. Attention is invited to the fact that because of the initial preloaded condition, the trunnion blocks are still under compression throughout their volume even at a miximum 'torque loa-d.

The foregoing arrangement is particularly characterized in its mode of operation in that the flexibility of the flexible medium can be advantageously controlled by the proper arrangement and judicious selection as to the number of the trunnion blocks as at 3| so as to effectively tune the natural frequency of the system out of the range of the frequencies of the exciting torque.

Particular attention is invited to .the arrangement disclosed in Fig. 2 wherein there is illustrated a flexible sprocket hub as contemplated herein which provides three basic parts, these parts being the hub structure 22, the flexible medium 3|] and the sprocket element 2|. It is important to understand 'that each of these parts are readily separable from the other. For example, the sprocket element can be conveniently and advantageously removed from portions of the hub by merely removing the snap ring 25 and removing the threaded end portion 38 of the stud 34 from the threaded aperture 39, thereby permitting the sprocket element to be moved axially to the left as shown in Fig. 2. In like manner the exible medium may be advantageously and conveniently removed from the hub 22 by merely removing the remainder of the stud bolts which, incidentally, are related to the hub by having the threaded end formations 38 disposed in the threaded aperture 39, thereby permitting axial movement to the left as shown in Fig. 2 of the flexible medium 30 to remove the flexible medium from the hub.

Reassembly of the respective elements may be advantageously accomplished by merely reversing the aforementioned procedure, and in this connection it may be stated that various sizes of sprockets may be substituted, each of said sprockets having the general Web structure to accommodate the hub in assembly.

6 Attention is invited to Figs. 3 and 4 which disclose a modified flexible sprocket hub designated in' its entirety by the numeral 50. The principles of operation are the same as that depicted with respect to the construction disclosed in Figs.

. 1 and 2, butin some applications it may be desirable to employ a pin construction, as disclosed in Fig. 4, as a substitute of the stud bolt construction as disclosed in Fig. 2.

In Fig. 4 the exible sprocket hub assembly 53 comprises, in general, a sprocket element 6|, a flanged hub 62 carried by a shaft 63, said sprocket element being arranged for a free t on the flanged hub 62 to permit restricted relative rotation therebetween and being maintained endwise by suitable means such as, for example, a snap ring E5, said sprocket element 6| and said flanged hub 62 having operatively disposed therebetween a flexible medium design-ated in its entirety bythe numeral 66 and comprising a plurality of trunnion blocks as at 61 operatively disposed within a retainer ring B8 which is carried for a free t by portions of the hub 62 and being maintained endwise by portions of the sprocket element 6| and portions of the flanged hub 22, each of said trunnion blocks 61 being respectively operatively associated With a pin 38 having end portions 'I0 respectively arranged to be received into an aperature 1| in a series spring relationship so that one pin would be associated with the sprocket while the next pin would be associated with the flanged hub as illustrated.

The foregoing arrangement is particularly characterized in its mode of operation in that the flexibility of the flexible medium can be controlled by the arrangement and number of the trunnion blocks as at 3| so as to tune the natural frequency of the system out of the range of the frequencies of the exciting torque.

The muscle-like trunnion blocks l|S`| are designed for uniform stress and linear deflection, all relative movement being accommodated by controlled displacement of the compressed rubber. It is notable that the bore 15 of the trunnion block 3| is of smaller diameter than the diameter of the pin 69, thereby providing a heavy press fit between these elements when they are assembled.

Moreover, individual trunnion blocks `6'! are press fitted into a pocket T6 disposed in the retainer ring EIB while the end portions 10 of the 'pins are received into the apertures which are alternately disposed in the sprocket 6| and the flanged hub 82, thereby to provide a series spring relationship.` A snug t is provided for the end portions 10 of the pin |59 in the apertures 1|.

In operation, it is notable that the sprocket 6| may be conveniently and advantageously removed from the hub assembly 62 by merely removing the snap ring 26 which will permit the sprocket 6| to be moved axially to the left as illustrated in Fig. 4. Thereafter, if it is so desired, the fiexible medium 66 may be removed by merely sliding it xially to the left until it is removed from the In this connection, it may be stated that various sizes of sprockets may be employed on the same hub structure. Replacement of a selected sprocket may be accomplished in the manner as hereinbefore described. This feature is particularly advantageous Where it is desired to employ different sized sprocket-s to accomplish different drive arrangements.

It is notable that the structure disclosed in Figs. 3 and 4 provides the same advantages of the preloaded trunnion blocks hereinbefore described with respect'tothestructu're disclosedin Figs. 1 iIldZ. -tion associated with the end portions of the pins The trunnion blocks 62 have aside porposite end ofsaid pin in alternative spaced relation withrespect to the flanged hub and sprocket thereby allowing volumetric expansion of said.

`trunnion blocks thus reducing the magnitude of the shock loads transmitted from the sprocket to the hub.

From the foregoing disclosure, it .may be observed that I have provided an improved flexible sprocket hub assembly which efficiently fulfills the objects thereof as hereinbefore set forth and which provides numerous advantages which may be summarized as follows:

1. Structurally simple, efficient and durable;

2. Economical to manufacture and readily adaptable to mass production manufacturing principles; and

3. The provision of a flexible sprocket hub particularly and advantageously applicable for employment in power transmission equip-ment Where freedom from vibration and shockis desired, the arrangement thereof being particularly characterized in employing a series spring principle of operation.

While I have illustrated preferred vembodiments of my invention, many modifications may be made without departing from the spirit of the invention, and I vdo not wish to be limited to the precise details of construction set forth, but Wish to avail myself of all changes within the scope of the appended claim.

I claim:

A flexible sprocket hub assembly comprising a sprocket Velement constituting the .driving-member, a angedhub carried bylashaft constituting the driven member, fs-aid sprocket element Abei-ng arranged for a free t on the iianged hub -to permit restricted relative rotation therebetween, means associated `with and carried by theiianged hub to maintain the sprocket element in its operative position wi-th respect to the flanged hub, said sprocket element :and said flanged h-ub having operatively disposed therebetween a flexible medium comprising a retainer ring and 'a pluralityof trunnion blocks press-fitted therein, said retainer ring 'being arranged for a free fit on v'the hub, arid a plurality of driving pins having end portions thereof alternatively secured to the sprocket element and the flanged hub vand the opposite ends of :said pins being tted within the trunnion blocks, thereby to reduce the magnitude of shock loads transmitted from the driving to the driven member.

ELMER L. MCINTYRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,815,894 Baker July 28,1931 1,861,390 Gunn May 31, 1932 1,978,939 Guy Oct. 30, 1934 2,038,020 Wylie Apr. 21, 1936 FOREIGN PATENTS Number Country Date 171,295 Great Britain Nov. 17, 1921 

